adobe+vermiculita insulation Other Oven Types Discuss adobe+vermiculita insulation in the Pizza Oven Design and Installation forums; what would be a good mixture for the insulation under the ovenfloor, and how thick it should be... adobe with ...

[danqui]

what would be a good mixture for the insulation under the ovenfloor, and how thick it should be... adobe with vermiculita??

[dmun]

You can use your vermiculite to insulate under the oven: a mixture of five to one by volume with portland cement will make vermiculite concrete, which will set up to a cork like consistency in about a week. Four inches is the minimum recommended under floor insulation.

[JoeyVelderrain]

Originally Posted by dmun

Four inches is the minimum recommended under floor insulation.

is this also the case under 2.5" thick firebrick floors?

what is the mixing recipe for perlcrete? I'm having trouble finding vermiculite in Louisiana, water retention is not our problem or...rather retaining too much water is a problem for plants here.

[dmun]

Yep, four inches all around. Perlite works the same as vermiculite, that's what I used. Full instructions here

[ThisOldGarageNJ]

I'm having trouble finding vermiculite in Louisiana

www.uline.com

They have 4 cubic foot bags about 22 dollars each.. Have you tried a pool supply, they sometimes sell it premixed with the concrete

Mark

[JoeyVelderrain]

Mark,
I bought some perlite at lowes, before I got your post. I think it will work out ok.
I also picked up a bag of pulverized limestone. The way I understand it, the less portland cement you use the better the perlcrete will work. What about the limestone? What is a good ratio to use?

[ThisOldGarageNJ]

the way I understand it the more lime you add the stickier it becomes,,, but im hoping someone else can answer this question better...

[kebwi]

I'm a little confused. Most vermcrete/perlcrete recipes are pure vermiculite/perlite and Portland, but occasionally I see references to mixing in lime.

Why? And how does one decide whether lime is a helpful additive for a particular application?

And is there any utility in using a higher a ratio of 6:1 or 7:1? I realize we may need 5:1 under the floor to achieve structural support, but on top of the dome we need much less support. Would a higher ratio provide better thermal insulation and still be strong enough to hold together?

Would it be advisable (or specifically *in*advisable to include a chicken wire matrix in the perlcrete (like putting standard mesh in standard concrete), especially at higher ratios? Would that help any?

[ThisOldGarageNJ]

there have been 10-1 mixes I've seen on here, Im pretty sure I used 6-1, I also mixed mine in a mixer as opposed to by hand,,(some dont recommen using a mixer) My point is, I dont see why you would need lime in ther vermicrete, I dont think its necessary.. In the stucco yes, I didnt use stucco I used the quikrete Surface Bonding Cement, or my needs it was easy to work with and adds structural strength to whatever you apply it to as well.. Hope that answers your question

Mark

[JoeyVelderrain]

Originally Posted by ThisOldGarageNJ

there have been 10-1 mixes I've seen on here, Im pretty sure I used 6-1, I also mixed mine in a mixer as opposed to by hand,,(some dont recommen using a mixer) My point is, I dont see why you would need lime in ther vermicrete, I dont think its necessary.. In the stucco yes, I didnt use stucco I used the quikrete Surface Bonding Cement, or my needs it was easy to work with and adds structural strength to whatever you apply it to as well.. Hope that answers your question

Mark

I hope I didn't hijack this thread but...

So use lime on the dome render but not needed on the hearth insulation?